1. Field of the Invention
This invention relates to a locking and release mechanism for a barrier, such as a barrier for a gate for controlling passenger access to a railway or rapid transit station or a public transport vehicle. In particular the invention relates to a locking and release mechanism for a gate having at least one stop member associated with the barrier and a locking member displaceable between a locking position in which it engages the stop member to prevent displacement of the barrier and a release position in which the barrier may be displaced.
The invention relates to a locking and release mechanism for a gate having means defining a passage for movement through the gate and at least one barrier means which is disposed in a blocking position at least when the gate is in a locked condition and is displaceable at least from its blocking position to a clear position when the gate is in a free condition, movement through the passage being substantially inhibited when the gate is in its locked condition and being substantially unhindered by the barrier means when the gate is in its free condition, at least during displacement of the barrier means from its blocking position to said clear position.
The locking and release mechanism may comprise at least one locking member movable between a locking position and a release position and at least one stop member displaceable between a rest position and a free position along at least one path, displacement of the stop member from its rest position at least along said path being prevented when the locking member is in its locking position and the stop member being displaceable at least along said path at least when the locking member is in its release position. The stop member of the locking and release mechanism may be associated with the barrier means of the gate so that the stop member is disposed in its rest position when the barrier means is disposed in its blocking position and the stop member is disposed in a free position when the barrier means is disposed in a clear position. Such gates and locking mechanisms are known and used, in particular in ticket barriers for controlling passenger access to railway and rapid transit stations.
2. Description of the Prior Art
A well-known and widely-used gate of the type described is the tripod turnstile, and embodiments of the locking and release mechanism according to the invention disclosed herein will be described in relation to a tripod turnstile.
A brief description of the general construction and functioning of a ticket barrier embodying a tripod turnstile gate follows but the mechanism according to the invention is not limited to such gates or barriers, and may also be applied to, inter alia, "paddle" type gates. The ticket barrier includes a structure defining a passage through which passengers can move and barrier means formed by the arms of the tripod turnstile. The turnstile is rotatably mounted so that one arm of the tripod is disposed in a blocking position which is usually substantially horizontal when the gate is in a locked condition so as to substantially inhibit the movement of passengers through the gate. When the gate is in its free condition, a passenger may rotate the tripod turnstile by manual action or body pressure, so that the initially horizontal arm of the turnstile which inhibited his passage through the gate in the locked condition is displaced, initially forwardly away from him and then downwardly to a clear position, while the passenger moves past it during this displacement and on out of the gate. At the same time the following arm of the tripod is moved upwardly and latterly forwardly behind the passenger and reaches its horizontally disposed, blocking position when the first-mentioned arm reaches its clear position. In normal use, the barrier then again reverts to a locked condition by the action of automatic control means and is unlocked by the presentation of a valid ticket to a ticket checking or validation device. Each time the gate is unlocked, an arm of the tripod can be displaced from its blocking position to a clear position and a single passenger can pass through.
Barriers of this type may also be operated under the supervision of an operative, as well as in conjunction with automatic ticket validators and the like. It is usually a requirement of gates of this type that the turnstile should be able to run free in conditions of power failure or emergency, as opposed to its normal mode of operation in which just one passenger is permitted to move through the gate each time the gate is unlocked. In the normal mode, the gate cannot be passed through in the absence of a valid ticket, without climbing over it or ducking under the barrier means, in the case of a tripod turnstile.
British Patent Specification No. 1,461,078 discloses a turnstile control mechanism comprising a shaft for connection to a stile or barrier, the shaft being mounted rotatably in a support structure, a detent mounted on the support structure for movement to a position in which it holds the shaft in a predetermined angular position, a pneumatic ram provided on the support structure for loading the detent into its shaft holding position and a valve associated with the ram and operable to release pneumatic pressure in the ram to thereby unload the detent and permit shaft rotation.
The pneumatic pressure can be set to a value such that the detent loading afforded thereby can be overcome to allow turnstile operation even without valve release of the pressure, albeit by exerting more than normal pressure on the barrier, so that if the barrier is used to control exit from a public place then in the event of, for example, fire and panic conditions, the barrier does not prevent exit even though a normal detent release is not effected.
Further desirable features to be sought in gates of this type are a facility for bi-directional operation so that the gate can cope with passenger flows in either direction and thereby reduce the number of gates to be installed at any given station, and a non-return arrangement, so that the barrier, when unlocked, can only be operated for movement through it in a direction appropriate to the ticket presented.
South African Patent Specification No 77/2551 discloses a control divide for a turnstile which comprises a rotatable member, a plurality of formations on the member first locking means which is engageable with at least one of the formations to prevent rotation of the member in the first direction but which permits rotation of the member in a second direction opposite to the first direction, a second locking means which is engageable with at least one of the formations to prevent rotation of the member in the second direction but which permits rotation of the member in the first direction, and means to disengage either the first or the second locking means from each formation to permit rotation of the member in the first direction, or in the second direction respectively.